JPWO2016181962A1 - Organic photoelectric conversion element - Google Patents

Abstract

An organic photoelectric conversion element having an active layer containing an organic semiconductor provided between a pair of electrodes consisting of an anode and a cathode, and an electron transporting layer containing a polymer containing nitrogen provided between the cathode and the active layer An organic photoelectric conversion device in which the number of nitrogen atoms (N) and the number of nitrogen cations (N +) contained in the polymer satisfy a relationship of (N +) / {(N +) + (N)} ≧ 0.2.

Description

  The present invention relates to an organic photoelectric conversion element.

  In recent years, an organic photoelectric conversion element having an active layer containing an organic semiconductor has attracted attention because an active layer can be produced by an inexpensive coating method. In order to improve the characteristics of the organic photoelectric conversion element, an organic photoelectric conversion element is proposed in which an electron transport layer having a function of selectively extracting electrons and blocking holes is provided between the cathode and the active layer. As an electron transport layer, for example, an electron transport layer using polyethyleneimine ethoxylate (PEIE) is known. (Non-Patent Document 1).

Ping Li, “Physical Chemistry and Chemical Physics”, September 18, 2014, Vol. 16, p. 23792-p. 23799

  The conversion efficiency of the organic photoelectric conversion element using the electron transport layer described in Non-Patent Document 1 is not always sufficient.

The present invention is as follows.
[1] an active layer containing an organic semiconductor provided between a pair of electrodes consisting of an anode and a cathode;
An organic photoelectric conversion element having an electron transport layer containing a polymer containing nitrogen provided between a cathode and an active layer,
An organic photoelectric conversion element in which the number of nitrogen atoms (N) contained in the polymer and the number of nitrogen cations (N ⁺ ) satisfy a relationship of (N ⁺ ) / {(N ⁺ ) + (N)} ≧ 0.2.
[2] The organic photoelectric conversion device according to [1], wherein the polymer containing nitrogen is a polymer containing an amino group.
[3] The organic photoelectric conversion device according to [2], wherein the polymer containing an amino group is a polyalkyleneimine derivative.
[4] The organic photoelectric conversion element according to any one of [1] to [3], wherein a substrate, a cathode, an electron transport layer, an active layer, and an anode are laminated in this order.
[5] The organic photoelectric conversion element according to any one of [1] to [4], wherein the cathode is an oxide.
[6] An organic thin-film solar cell including the organic photoelectric conversion element according to any one of [1] to [5].
[7] An organic optical sensor comprising the organic photoelectric conversion element according to any one of [1] to [5].
[8] A step of forming a coating film by applying a solution containing a polymer containing nitrogen atoms on the cathode, a step of cleaning the surface of the coating film, and forming an active layer on the cleaned coating film The manufacturing method of the organic photoelectric conversion element including a process and the process of forming an anode.
A step of forming a hole transport layer on the active layer may be included after the step of forming the active layer and before the step of forming the anode.
[9] The method for producing an organic photoelectric conversion element according to [8], wherein the washing step is a washing step using an organic acid.

<Organic photoelectric conversion element>
The present invention is an organic photoelectric conversion element including an active layer including an organic semiconductor provided between a pair of electrodes, and an electron transporting layer including a polymer including a nitrogen atom provided between a cathode and an active layer. The number of nitrogen atoms (ie, uncharged nitrogen atoms) present in the polymer (N) and the number of nitrogen cations (ie, cationic nitrogen atoms) (N ⁺ ) are (N ⁺ ) / {(N ⁺ ) The present invention relates to an organic photoelectric conversion element having a relationship of + (N)} ≧ 0.2.

<Configuration of organic photoelectric conversion element>
The organic photoelectric conversion element of this invention has an electron carrying layer containing the polymer containing nitrogen between a cathode and an active layer. Hereinafter, a photoelectric conversion element in which a substrate, a cathode, an electron transport layer containing a polymer containing nitrogen, an active layer, and an anode are laminated in this order will be described. The present invention is not limited to the photoelectric conversion elements stacked in the above order.

(substrate)
The organic photoelectric conversion element of the present invention may include a substrate.
The material of the substrate is not particularly limited as long as it can form an electrode on the substrate and does not change chemically when a layer containing an organic compound is formed. As the substrate, for example, a plate-shaped substrate containing glass, plastic, polymer film, silicon, aluminum foil, copper foil, stainless steel alloy and the like and having two main surfaces facing each other can be used. A substrate in which a thin film of a conductive material that can be a cathode material such as indium / tin oxide is provided on one main surface of the substrate in advance may be used.

(electrode)
The organic photoelectric conversion element of the present invention includes a pair of electrodes composed of an anode and a cathode.
At least one of the anode and the cathode is preferably a transparent or translucent electrode. The light incident from the transparent or translucent electrode is absorbed in the active layer by one or more compounds selected from the group consisting of an electron accepting compound and an electron donating compound described later, whereby electrons and holes are generated. Combined excitons are generated. When the exciton moves in the active layer and reaches the heterojunction interface where the electron accepting compound and the electron donating compound are adjacent to each other, the difference between the HOMO energy and the LUMO energy at the interface causes the electrons and holes to be separated. Charges (electrons and holes) are generated that can separate and move independently. The generated electric charges are taken out as electric energy (current) by moving to the electrodes.

  When the organic photoelectric conversion element of the present invention includes a substrate, the electrode provided on the substrate side may be a cathode or an anode.

  As the electrode material, a metal, a conductive polymer, or the like can be used. For example, one or more selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium The metal or alloy is raised. Specific examples of the alloy include magnesium-indium alloy, magnesium-aluminum alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, and calcium-aluminum alloy.

  The electrode material is selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, and ytterbium. An alloy of one or more metals selected from the group consisting of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, and tin may be used. Specific examples of the alloy include magnesium-silver alloy and indium-silver alloy.

  As the electrode material, graphite, graphite intercalation compounds, polyaniline and derivatives thereof, polythiophene and derivatives thereof, and the like may be used.

  As the electrode material, a dispersion liquid of nanoparticles, nanowires, and nanotubes of a conductive material may be used.

  When the polymer containing nitrogen used for the organic photoelectric conversion element of the present invention contains a functional group capable of forming a hydrogen bond such as a hydroxyl group or a carboxyl group, an electrode material having a functional group capable of forming a hydrogen bond with the functional group is prepared. It is preferable to use it. By using such an electrode material, the polymer having nitrogen tends to adhere firmly to the electrode surface and process resistance tends to be improved. As such an electrode material, a conductive material that is an oxide (preferably a metal oxide) such as indium tin oxide (ITO), indium zinc oxide (IZO), and tin oxide is preferable.

  Examples of the transparent or translucent electrode include a conductive metal oxide film and a translucent metal thin film. Specifically, indium oxide, zinc oxide, tin oxide, titanium oxide, and composite films thereof made of conductive materials such as ITO, IZO, gold, platinum, silver, and copper are listed. . Organic transparent conductive films such as polyaniline and derivatives thereof and polythiophene and derivatives thereof may be used. When water is used as the cleaning solution in the step of cleaning the coating film for forming the electron transport layer, nitrogen atoms in the polymer containing nitrogen react with hydroxyl groups on the electrode surface and are converted to nitrogen cations. From the viewpoint, the cathode is preferably a metal oxide that easily reacts with moisture in the atmosphere to form a hydroxyl group, and specifically, an oxide containing tin oxide, zinc oxide, or titanium oxide is preferred.

  The electrode is formed by forming a thin film of the conductive material on one main surface of the substrate by vacuum deposition, sputtering, ion plating, plating, or the like, and then patterning the thin film of the conductive material. can do. The patterning can be performed by any suitable method, but can be performed, for example, by photolithography, etching, or the like.

(Electron transport layer)

The electron transport layer contained in the organic photoelectric conversion element of the present invention contains a polymer containing nitrogen. The number of nitrogen atoms (N) and the number of nitrogen cations (N ⁺ ) in the nitrogen-containing polymer have a relationship of (N ⁺ ) / {(N ⁺ ) + (N)} ≧ 0.2, and (N ⁺ ) / {(N ⁺ ) + (N)} ≧ 0.5 is preferable.
The value of (N ⁺ ) / {(N ⁺ ) + (N)} can be obtained by subjecting an electron transport layer containing a polymer containing nitrogen to X-ray photoelectron spectroscopy (XPS).
In the polymer having nitrogen, the number of nitrogen atoms (N) corresponds to the total number of primary amino group, secondary amino group and tertiary amino group contained in the polymer, and the number of nitrogen cations (N ⁺ ) is This corresponds to the number of substituted or unsubstituted ammonium cations contained in the polymer.

A part or all of the nitrogen-containing polymer may be neutralized with a Bronsted acid. Examples of the Bronsted acid include inorganic acids such as hydrochloric acid and hydrobromic acid, and organic acids such as formic acid, acetic acid, oxalic acid and malonic acid.
The polymer containing nitrogen is preferably a polymer containing an amino group.
The nitrogen atom of the amino group in the polymer containing an amino group may have a hydroxyl group, a carboxyl group, a sulfonic acid group, or a phosphoric acid group substituent (for example, a hydroxyl group, a carboxyl group, a sulfonic acid group, or a phosphoric acid group). It may be bonded to a group such as a good alkyl group.

The amino group may be a primary amino group, a secondary amino group, or a tertiary amino group. In the polymer containing an amino group, one or more repeating units having one or more amino groups selected from the group consisting of a primary amino group, a secondary amino group, and a tertiary amino group are random, block, An alternating or graft copolymerized polymer. Moreover, the polymer containing an amino group may have a repeating unit having no amino group. The polymer containing an amino group may be partially or completely neutralized with a Bronsted acid.

Polymers containing amino groups include polyvinylamine, polyvinylalkylamine, polyalkyleneimine, polyaniline, polynucleotide, polyallylamine, polyalkyleneamine, polyvinylamine derivatives, polyvinylalkylamine derivatives, polyalkyleneimine derivatives, polyaniline derivatives. At least one selected from the group consisting of derivatives, derivatives of polynucleotides, derivatives of polyallylamine and derivatives of polyalkyleneamine is preferably used. A copolymer obtained by copolymerizing two or more repeating units constituting these polymers can also be suitably used. Among these, at least one selected from the group consisting of polyvinylamine, polyallylamine, polyalkyleneamine, polyvinylamine derivatives, polyallylamine derivatives and polyalkyleneamine derivatives is more preferable. In particular, a polyalkyleneimine derivative is preferred because of its high amino group density.
As a derivative of polyvinylamine, a part or all of hydrogen atoms (for example, hydrogen atoms bonded to nitrogen atoms) of polyvinylamine have a substituent (for example, hydroxyl group, carboxyl group, sulfonic acid group or phosphoric acid group). A polymer substituted with an alkyl group which may be substituted (substituted polybilylamine), a polymer in which a part or all of nitrogen of polyvinylamine is a cationic nitrogen atom, a part or all of nitrogen of substituted polyvinylamine Are polymers in which is a cationic nitrogen atom.
The same applies to polyvinylalkylamine derivatives, polyalkyleneimine derivatives, polyaniline derivatives, polynucleotide derivatives, polyallylamine derivatives, and polyalkyleneamine derivatives.

The polyalkyleneimine is, for example, an alkyleneimine having 2 to 8 carbon atoms such as ethyleneimine, propyleneimine, butyleneimine, dimethylethyleneimine, pentyleneimine, hexyleneimine, heptyleneimine, octyleneimine, especially alkylene having 2 to 4 carbon atoms. It is a polymer obtained by polymerizing one or more of imines by a conventional method.
Polyalkyleneimines having various molecular weights can be synthesized by selecting the production method, and linear or branched ones can be synthesized. For example, linear polyethyleneimine has the formula:

（式中、nは7〜10000の範囲である）で表すことができる。また、分岐状のポリエチレンイミンは例えば式：

(Where n is in the range of 7 to 10,000). The branched polyethyleneimine is represented by the formula:

で表すことができる。ポリアルキレンイミンは、分子骨格中に１級アミノ基、２級アミノ基および３級アミノ基を含む。
ポリアルキレンイミンの誘導体としては、ポリアルキレンイミンが有する水素原子（例えば、窒素原子に結合した水素原子）の一部又は全部が置換基（例えばヒドロキシル基、カルボキシル基、スルホン酸基またはリン酸基）を有していてもよいアルキル基等で置換されたポリマー（置換ポリアルキレンイミン）、ポリアルキレンイミンが有する窒素の一部または全部がカチオン性窒素原子であるポリマー、置換ポリアルキレンイミンが有する窒素の一部または全部がカチオン性窒素原子であるポリマーがあげられる。
ポリアルキレンイミンの誘導体は、例えば、ポリアルキレンイミンを種々の化合物と反応させて化学的に変性させたポリマーである。
ポリアルキレンイミンの誘導体は、例えば、ポリアルキレンイミンを、アルデヒド、ケトン、アルキルハライド、イソシアネート、チオイソシアネート、アルケン、アルキン、ビニル化合物（アクリロニトリル等）、エポキシ化合物（エピクロルヒドリン等）、シアナマイド、グアニジン、尿素、有機酸（脂肪酸等）、酸無水物、アシルハライドと反応させて変性させることにより製造できる。
ポリアルキレンイミンの誘導体は、例えば、ポリアルキレンイミンまたはポリアルキレンイミンを種々の化合物と反応させて化学的に変性させたポリマーを、ブレンステッド酸、金属酸化物等と反応させて変性させることにより製造できる。
ポリアルキレンイミンおよびポリアルキレンイミンの誘導体は製法によって様々な構造をとり得るが、本発明におけるポリアルキレンイミンおよびポリアルキレンイミンの誘導体は直鎖あるいは分岐鎖のいずれでもよい。またポリアルキレンイミンおよびポリアルキレンイミンの誘導体は様々な分子量をとりうるが、本発明で用いるポリアルキレンイミンおよびポリアルキレンイミンの誘導体の重量平均分子量は通常300〜400,000の範囲内である。特に重量平均分子量が10,000〜400,000、とりわけ50,000〜200,000の範囲であるとより好ましい。 ポリアルキレンイミンの誘導体としては、ポリアルキレンイミン鎖に、直鎖状または分岐状の置換基を有する重合体を用いることができる。
ポリアルキレンイミンの誘導体の中では、ポリエチレンイミンの誘導体が好ましい。ポリエチレンイミンの誘導体としては、ポリエチレンイミンにアルキル基、アルキレンオキサイド基、アミノ基あるいはアリール基を導入したポリエチレンイミン誘導体、ポリエチレンイミンに水酸基等の架橋性基を導入して得られるポリエチレンイミン誘導体等を挙げることができる。中でも、エチレンオキサイド基を導入したエトキシ化ポリエチレンイミンが好ましい。

It can be expressed as The polyalkyleneimine contains a primary amino group, a secondary amino group, and a tertiary amino group in the molecular skeleton.
As a derivative of polyalkyleneimine, a part or all of hydrogen atoms (for example, hydrogen atom bonded to nitrogen atom) of polyalkyleneimine are substituted (for example, hydroxyl group, carboxyl group, sulfonic acid group or phosphoric acid group). A polymer substituted with an alkyl group or the like which may have a substituent (substituted polyalkyleneimine), a polymer in which part or all of the nitrogen of the polyalkyleneimine is a cationic nitrogen atom, or the nitrogen of the substituted polyalkyleneimine Examples thereof include polymers in which some or all of them are cationic nitrogen atoms.
The derivatives of polyalkyleneimine are, for example, polymers obtained by chemically modifying polyalkyleneimine by reacting with various compounds.
Polyalkyleneimine derivatives include, for example, polyalkyleneimine, aldehyde, ketone, alkyl halide, isocyanate, thioisocyanate, alkene, alkyne, vinyl compound (acrylonitrile, etc.), epoxy compound (epichlorohydrin, etc.), cyanamide, guanidine, urea, It can be produced by reacting with an organic acid (such as a fatty acid), an acid anhydride, or an acyl halide for modification.
Polyalkyleneimine derivatives are produced, for example, by reacting polyalkyleneimine or a polymer that has been chemically modified by reacting polyalkyleneimine with various compounds and reacting with Bronsted acid, metal oxide, etc. it can.
The polyalkyleneimine and the polyalkyleneimine derivative can have various structures depending on the production method, but the polyalkyleneimine and the polyalkyleneimine derivative in the present invention may be either linear or branched. Polyalkyleneimines and polyalkyleneimine derivatives can have various molecular weights, but the weight average molecular weights of the polyalkyleneimine and polyalkyleneimine derivatives used in the present invention are usually in the range of 300 to 400,000. In particular, the weight average molecular weight is more preferably in the range of 10,000 to 400,000, especially 50,000 to 200,000. As the polyalkyleneimine derivative, a polymer having a linear or branched substituent in the polyalkyleneimine chain can be used.
Among the polyalkyleneimine derivatives, polyethyleneimine derivatives are preferred. Examples of the polyethyleneimine derivatives include polyethyleneimine derivatives obtained by introducing an alkyl group, alkylene oxide group, amino group or aryl group into polyethyleneimine, and polyethyleneimine derivatives obtained by introducing a crosslinkable group such as a hydroxyl group into polyethyleneimine. be able to. Of these, ethoxylated polyethyleneimine into which an ethylene oxide group has been introduced is preferred.

  The thickness of the electron transport layer is usually preferably 5 nm or less, and more preferably 2 nm or less.

(Active layer)
The active layer is sandwiched between a pair of electrodes. For the active layer, a mixture of an electron-accepting compound (n-type semiconductor) and an electron-donating compound (p-type semiconductor) can be used. For example, a bulk hetero type active layer may be mentioned. The active layer plays a role of generating charges (holes and electrons) by using the energy of incident light, and thus has an essential function for the organic photoelectric conversion element.

  The active layer included in the photoelectric conversion element preferably contains an electron donating compound and an electron accepting compound.

  Since the electron donating compound and the electron accepting compound are relatively determined from the energy level of the energy level of these compounds, one compound can be either an electron donating compound or an electron accepting compound.

  Examples of the electron donating compound include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, oligothiophene and derivatives thereof, polyvinylcarbazole and derivatives thereof, polysilane and derivatives thereof, and aromatic amines in side chains or main chains. And polysiloxane derivatives, polyaniline and derivatives thereof, polythiophene and derivatives thereof, polypyrrole and derivatives thereof, polyphenylene vinylene and derivatives thereof, polythienylene vinylene and derivatives thereof, and the like.

Examples of the electron-accepting compound include oxadiazole derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives, fluorenone derivatives, diphenyldicyanoethylene and derivatives thereof, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline and its derivatives, polyquinoline and its derivatives, polyquinoxaline and its derivatives, polyfluorene and its derivatives, fullerenes and derivatives thereof such as C _60, bathocuproine etc. Phenanthrene derivatives, metal oxides such as titanium oxide, carbon nanotubes, and the like. As the electron-accepting compound, titanium oxide, carbon nanotube, fullerene, and fullerene derivatives are preferable, and fullerene and fullerene derivatives are more preferable.

Examples of _{fullerene, C 60 fullerene, C 70 fullerene, C 76 fullerene, C 78 fullerene,} such as _{C 84} fullerene, and the like.

The fullerene _{derivative, C 60} fullerene _{derivatives, C 70} fullerene _{derivatives, C 76} fullerene _{derivatives, C 78} fullerene _{derivatives, C 84} fullerene derivatives. Specific examples of the fullerene derivative include the following.

Examples of fullerene derivatives include [6,6] phenyl-C ₆₁ butyric acid methyl ester (C ₆₀ PCBM, [6,6] -Phenyl C ₆₁ butyric acid methyl ester), [6,6] phenyl-C ₇₁ butyric acid methyl ester Esters (C ₇₀ PCBM, [6,6] -Phenyl C ₇₁ butyric acid
methyl ester), [6,6] phenyl-C ₈₅ butyric acid methyl ester (C ₈₄ PCBM, [6,6] -Phenyl C ₈₅ butyric acid methyl ester), [6,6] thienyl-C ₆₁ butyric acid methyl ester ([[ 6,6] -Thienyl C ₆₁ butyric acid methyl ester).

  When a fullerene derivative is used as the electron-accepting compound, the ratio of the fullerene derivative is preferably 10 to 1000 parts by weight and preferably 20 to 500 parts by weight with respect to 100 parts by weight of the electron-donating compound. More preferred.

  The thickness of the active layer is usually 1 nm to 100 μm, preferably 2 nm to 1000 nm, more preferably 5 nm to 500 nm, and further preferably 20 nm to 200 nm.

  As described above, the active layer may be a bulk hetero single layer in which an electron-accepting compound and an electron-donating compound are mixed, or may be composed of a plurality of layers. In the case of a plurality of layers, a heterojunction type in which an electron accepting layer containing an electron accepting compound and an electron supplying layer containing an electron donating compound are joined may be used. For example, a heterojunction type in which an electron-accepting layer containing a fullerene derivative and an electron-donating layer containing P3HT are joined can be given.

The proportion of the electron-accepting compound in the bulk hetero type active layer containing the electron-accepting compound and the electron-donating compound is preferably 10 to 1000 parts by weight with respect to 100 parts by weight of the electron-donating compound. More preferred is 500 parts by weight.
The organic photoelectric conversion device of the present invention may have an additional layer such as a hole transport layer.

(Hole transport layer)
The hole transport layer is provided between the anode and the active layer, and has a function of selectively extracting holes, an electronic block function, and the like. By providing the hole transport layer, a more efficient photoelectric conversion element can be obtained. Examples of the compound used for the hole transport layer include polymer compounds such as PEDOT: PSS, polyaniline, and polythiophene, and oxides such as molybdenum oxide and tungsten oxide.

(Constitution)
The example of the structure which the organic photoelectric conversion element of this invention can take is shown below.
a) Anode / active layer / electron transport layer / cathode b) Anode / hole transport layer / active layer / electron transport layer / cathode c) Anode / electron supply layer / electron accepting layer / electron transport layer / cathode d) Anode / hole transport layer / electron supply layer / electron accepting layer / electron transport layer / cathode (here, the symbol “/” indicates that the layers sandwiching the symbol “/” are adjacent to each other) Show.)

  The above configuration may be either a form in which the anode is provided on the side closer to the substrate or a form in which the cathode is provided on the side closer to the substrate. Each of the above layers may be configured as a single layer or a laminate of two or more layers.

In the organic photoelectric conversion device of the present invention, the electron transport layer located between the active layer and the cathode is a layer containing a polymer containing nitrogen, and the number of nitrogen atoms (N) and the number of nitrogen cations (N ⁺ ). Are in a relationship of (N ⁺ ) / {(N ⁺ ) + (N)} ≧ 0.2, high electron extraction efficiency can be obtained, and photoelectric conversion characteristics can be improved.

<Manufacturing method>
The organic photoelectric conversion element of the present invention includes a step of forming a coating film by applying a solution containing a polymer containing nitrogen on the cathode, a step of cleaning the surface of the coating film, and a step of cleaning the coating film. It can be manufactured by a manufacturing method including a step of forming an active layer and a step of forming an anode.
The organic photoelectric conversion device of the present invention typically has the above-described configurations a) to d).
Since the organic photoelectric conversion element having the configuration b) is preferable, a method for producing the organic photoelectric conversion element having the configuration b) will be described below, but the present invention is not limited to the configuration.
Hereinafter, a step of forming a coating film by applying a solution containing a polymer containing nitrogen on the cathode, a step of cleaning the surface of the coating film, a step of forming an active layer on the coating film, and the activity A method for producing an organic photoelectric conversion element including a step of forming a hole transport layer on a layer and a step of forming an anode on the hole transport layer will be described.

(Process for forming coating film)
The electron transport layer can be obtained, for example, from a step of forming a coating film by applying a solution containing the above-mentioned nitrogen-containing polymer on the cathode and a step of cleaning the surface of the coating film.

  Examples of the method for forming the coating film include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and screen printing. Application methods such as gravure printing, flexographic printing method, offset printing method, ink jet printing method, dispenser printing method, nozzle coating method, slot die coating method, capillary coating method and the like.

  As a solvent used for the solution containing the polymer containing nitrogen, water or an organic solvent can be used. Depending on the type of polymer containing nitrogen, a solvent having high solubility and high storage stability for a long time can be selected. Examples of the organic solvent include alcohol. Examples of the alcohol include methoxyethanol and 2-propanol.

The coated film is preferably subjected to the next washing step in an undried state. When completely dried, the polymer containing nitrogen is solidified by the washing step, and therefore, it tends to be difficult to expose a region having a high nitrogen cation concentration in the vicinity of the electrode by washing. As a method for maintaining the undried state, it is preferable to use a sealed container during storage and transfer of the coating film.

(Process to clean the coating film surface)
The coating film surface can be subjected to a cleaning treatment to increase the content of nitrogen cations. Nitrogen atoms in the polymer containing nitrogen are converted into nitrogen cations by hydrogen bonding with hydroxyl groups on the lower electrode surface, and there is a region with a higher nitrogen cation concentration in the vicinity of the electrode. The cleaning treatment is effective as a step of exposing the region having a high nitrogen cation concentration. Here, the cleaning treatment includes a step of bringing the cleaning solution into contact with the coating film surface and a step of removing the cleaning solution remaining on the coating film surface thereafter. As a method for bringing the cleaning solution into contact with the coating film surface, a method of immersing in the cleaning solution, a method of pouring the cleaning solution from a nozzle, a method of spraying the cleaning solution, or the like can be used. As the cleaning solution, a solvent that dissolves the polymer containing nitrogen can be used. As the cleaning solution, for example, water or an acidic aqueous solution can be used. When an acidic aqueous solution is used, it is preferably acidic enough not to dissolve the lower electrode and the like, and a solution containing an organic acid such as acetic acid, butyric acid, formic acid or citric acid is preferred. When acetic acid is used as the organic acid, an acetic acid aqueous solution having an acetic acid concentration of 5 to 90% by weight is preferred, an acetic acid aqueous solution having an acetic acid concentration of 25 to 80% by weight is more preferred, and an acetic acid aqueous solution having an acetic acid concentration of 50 to 70% by weight is preferred. Further preferred. As a method for removing the cleaning solution from the surface of the coating film, a drying method such as natural drying by air drying, drying under reduced pressure, or heat drying at a temperature below which the polymer containing nitrogen is not decomposed can be used.
The value of (N ⁺ ) / {(N ⁺ ) + (N)} can be obtained by subjecting the obtained electron transport layer containing a polymer containing nitrogen to X-ray photoelectron spectroscopy (XPS).

(Process of forming active layer)
Next, an active layer is formed on the electron transport layer according to a conventional method. In the case of producing an organic photoelectric conversion device having the above configuration a) or b), the step of forming the active layer is a coating liquid in which an electron accepting compound and an electron donating compound are mixed on the electron transport layer. The process of apply | coating. In the case of producing an organic photoelectric conversion device having the above configuration c) or d), a step of forming an electron-accepting layer by applying a coating liquid containing an electron-accepting compound on the electron-transporting layer; Forming an electron supply layer by applying a coating liquid containing an electron donating compound on the electron accepting layer. The active layer can be formed by applying on the electron transporting layer a coating liquid obtained by mixing any of the aforementioned suitable active layer materials and a solvent. Examples of the solvent include unsaturated hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decalin, bicyclohexyl, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, carbon tetrachloride, chloroform, dichloromethane, Halogenated saturated hydrocarbon solvents such as dichloroethane, chlorobutane, bromobutane, chloropentane, bromopentane, chlorohexane, bromohexane, chlorocyclohexane and bromocyclohexane, and halogenated unsaturated hydrocarbon solvents such as chlorobenzene, dichlorobenzene and trichlorobenzene , Ether solvents such as tetrahydrofuran and tetrahydropyran. Two or more kinds of solvents may be added from the viewpoint of applicability, solubility of solute components, storage stability, and the like, using the above solvent as a main solvent.

  The active layer can be formed by spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, gravure. Coating methods such as printing, flexographic printing, offset printing, inkjet printing, dispenser printing, nozzle coating, slot die coating, and capillary coating can be used.

(Step of forming a hole transport layer)
Next, a hole transport layer is formed on the active layer. In the case of forming a polymer type hole transport layer, the hole transport layer can be formed by applying a coating liquid containing the polymer and a solvent. As a coating liquid for the hole transport layer, a liquid dispersed in water or an organic solvent containing PEDOT: PSS, polyaniline, polythiophene, or the like can be used. Examples of the coating method include the same methods as those used for the active layer. Similarly, when a nanoparticle dispersion such as molybdenum oxide is used, it can be formed by a coating method. Molybdenum oxide or the like can also be formed by a vacuum evaporation method.

(anode)
Next, an electrode to be an anode is formed on the hole transport layer. When a dispersion liquid of conductive material nanoparticles, nanowires, nanotubes, or the like is used for the anode, it can be formed by a coating method as in the active layer. When a metal film such as aluminum or silver is used as the anode, it can also be formed by a vacuum deposition method.

<Operation>
The operation mechanism of the organic photoelectric conversion element will be briefly described. The incident light energy that has passed through the transparent or translucent electrode and entered the active layer is absorbed by one or more selected from the group consisting of an electron-accepting compound and an electron-donating compound, and electrons and holes are combined. Excitons are generated. When the generated excitons move and reach the heterojunction interface where the electron-accepting compound and the electron-donating compound are bonded, the difference between the HOMO energy and the LUMO energy at the interface causes the electrons and holes to be separated. Charges (electrons and holes) are generated that can separate and move independently. The generated charges move to the electrodes (cathode and anode), respectively, and can be taken out as electric energy (current) outside the device.

<Application>
The organic photoelectric conversion element manufactured by the manufacturing method of the present invention irradiates light such as sunlight from one or more selected from the group consisting of a transparent or translucent cathode and anode, so that a photovoltaic power is generated between the electrodes. And can be operated as an organic thin film solar cell. It can also be used as an organic thin film solar cell module by integrating a plurality of organic thin film solar cells.

  In the organic photoelectric conversion device manufactured by the manufacturing method of the present invention, light is transmitted through an electrode that is transparent or translucent in a state where a voltage is applied between the cathode and the anode, or in a state where no voltage is applied. The incident photocurrent flows. Therefore, the organic photoelectric conversion element manufactured by the manufacturing method of the present invention can be operated as an organic photosensor. It can also be used as an organic image sensor by integrating a plurality of organic photosensors.

  Examples will be shown below for illustrating the present invention in more detail, but the present invention is not limited to these examples.

Example 1
(Production and evaluation of organic thin-film solar cells)
A glass substrate on which an ITO film with a thickness of 150 nm was formed by sputtering was washed with acetone and then subjected to ultraviolet ozone treatment to produce an ITO electrode having a clean surface. As a polymer containing nitrogen, a solution obtained by diluting polyethyleneimine ethoxylate (PEIE) (manufactured by Aldrich, trade name polyethyleneimine, 80% ethoxylated solution, weight average molecular weight to 70,000) 1/50 times with deionized water, It apply | coated on the ITO board | substrate by spin coating. The thickness of the PEIE coating film was about 5 nm. Subsequently, using a spin coater, cleaning treatment was performed for 30 seconds at a rotation speed of 300 rpm while dropping deionized water onto the surface of the PEIE film. The substrate after the cleaning treatment was subjected to heat treatment at 120 ° C. for 10 minutes using a hot plate to obtain the electron transport layer 1.

The ratio of the number of nitrogen cations to the total number of nitrogen atoms (that is, the total number of nitrogen atoms and nitrogen cations) in the obtained electron transport layer 1 was determined by the following method.
(1) X-ray photoelectron spectroscopy (XPS) (x-ray photoelectron spectroscopy, manufactured by Ulvac PHI, apparatus name: Quantera SXM) is used.
(2) N1s signal peak observed at binding energy (BE) of about 400 eV is analyzed and two peaks are derived from nitrogen atom (BE = 400 eV) and nitrogen cation (BE = 401 ± 0.1 eV). To separate.
(3) From the ratio of each peak area, the ratio of nitrogen cations to the total nitrogen atoms was determined.

The results are listed in Table 1.

Next, polymer compound A, which is a polymer corresponding to a p-type semiconductor material, and C ₆₀ PCBM (trade name nanom spectra E100, manufactured by Frontier Carbon Co.) corresponding to an n-type semiconductor material are added to an orthodichlorobenzene solvent ( Polymer compound A: 0.5 mass%, PCBM: 1.0 mass%) After stirring at 80 ° C. for 3 hours, a coating solution for the active layer was obtained. The high molecular compound A is obtained by the synthesis method described in Example 1 of International Publication No. W2013 / 051676. The coating liquid was applied onto the electron transport layer 1 by spin coating to produce an active layer containing the polymer compound A and C60PCBM. The thickness of the active layer was about 120 nm.

  Next, a polythiophene derivative (manufactured by Solvay, product name: AQ1300) was applied on the active layer by spin coating, and then subjected to heat treatment on a hot plate at 70 ° C. for 5 minutes to form the hole transport layer 1. . The thickness of the hole transport layer 1 was about 70 nm.

  Next, after applying a silver nanowire dispersion liquid (manufactured by Cambrios, trade name Clear-Ohm Ink-N) on the hole transport layer 1 by spin coating, it is treated on a hot plate at 70 ° C. for 5 minutes. Then, an anode was formed, and an organic thin film solar cell 1 was obtained.

The shape of the obtained organic thin film solar cell 1 was a square of 10 mm × 10 mm. The obtained organic thin film solar cell is irradiated with constant light using a solar simulator (trade name CEP-2000: AM1.5G filter, irradiance 100 mW / cm ² , manufactured by Spectrometer Co., Ltd.), and the generated current and voltage are measured. The photoelectric conversion efficiency, short-circuit current density, open-circuit voltage, and fill factor (curve factor) were determined. The measurement results are shown in Table 2.

Example 2
An electron transport layer 2 was prepared in the same manner as in Example 1 except that an aqueous solution containing 5% by weight of acetic acid was used instead of deionized water in the cleaning treatment of the PEIE coating film in the preparation of the electron transport layer. The XPS analysis results are listed in Table 1.

Example 3
Electron transport 3 was prepared in the same manner as in Example 1 except that an aqueous solution containing 25% by weight of acetic acid was used in the cleaning treatment of the PEIE coating film in the preparation of the electron transport layer. Furthermore, the organic thin film solar cell containing it was produced similarly to Example 1. The XPS analysis results of the electron transport layer 3 are shown in Table 1, and the photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Example 4
An electron transport layer 4 was prepared in the same manner as in Example 1 except that an aqueous solution containing 50% by weight of acetic acid was used in the cleaning treatment of the PEIE coating film in the preparation of the electron transport layer. Furthermore, the organic thin film solar cell containing it was produced similarly to Example 1. The XPS analysis results of the electron transport layer 4 are shown in Table 1, and the photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Example 5
In the active layer, PCE10 corresponding to p-type semiconductor material (trade name: OS010, manufactured by 1-Material Co.) and C ₇₀ PCBM (trade name ADS71BFA) corresponding to n-type semiconductor material, which is used are used. And the organic thin-film solar cell was produced by the same method as Example 1 except having used Ag (film thickness of 60 nm) by vacuum deposition in the anode. The photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Example 6
An organic thin-film solar cell was produced in the same manner as in Example 5 except that the electron transport 2 described in Example 2 was used. The photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Example 7
An organic thin film solar cell was produced in the same manner as in Example 5 except that Compound A was used as the polymer corresponding to the p-type semiconductor. Table 2 shows the photoelectric conversion characteristics of the obtained organic thin film solar cell.

Example 8
An organic thin film solar cell was produced in the same manner as in Example 6 except that Compound A was used as the polymer corresponding to the p-type semiconductor. Table 2 shows the photoelectric conversion characteristics of the obtained organic thin film solar cell.

Example 9
An organic thin-film solar cell was produced in the same manner as in Example 5 except that molybdenum trioxide (film thickness was about 15 nm) was used as the hole transport layer by vacuum deposition. The photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Example 10
An organic thin film solar cell was produced in the same manner as in Example 6 except that molybdenum trioxide (film thickness was about 15 nm) was used as the hole transport layer by vacuum deposition. The photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Comparative Example 1
After applying the PEIE layer, an organic thin film solar cell was produced in the same manner as in Example 1 except that the electron transport layer 5 that had not been subjected to the cleaning treatment was used. The XPS analysis results of the electron transport layer 5 are shown in Table 1, and the photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Comparative Example 2
An electron transport layer 6 was produced in the same manner as in Comparative Example 1 except that the electron transport layer 6 obtained from a solution obtained by diluting the PEIE layer with deionized water 1/100 times was used. Furthermore, the organic thin film solar cell containing them was produced similarly to the comparative example 1. The photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

Comparative Example 3
An electron transport layer 7 was produced in the same manner as in Comparative Example 1 except that the electron transport layer 7 obtained from a solution obtained by diluting the PEIE layer with deionized water 1/300 times was used. Furthermore, the organic thin film solar cell containing it was produced similarly to the comparative example 1. The photoelectric conversion characteristics of the obtained organic thin film solar cell are shown in Table 2.

  ADVANTAGE OF THE INVENTION According to this invention, the organic photoelectric conversion element which has the outstanding photoelectric conversion efficiency can be provided.

Claims (9)

An active layer containing an organic semiconductor provided between a pair of electrodes consisting of an anode and a cathode;
An organic photoelectric conversion element having an electron transport layer containing a polymer containing nitrogen provided between a cathode and an active layer,
An organic photoelectric conversion element in which the number of nitrogen atoms (N) contained in the polymer and the number of nitrogen cations (N ⁺ ) satisfy a relationship of (N ⁺ ) / {(N ⁺ ) + (N)} ≧ 0.2.   The organic photoelectric conversion element according to claim 1, wherein the polymer containing nitrogen is a polymer containing an amino group.   The organic photoelectric conversion element according to claim 2, wherein the polymer containing an amino group is a polyalkyleneimine derivative.   The organic photoelectric conversion element as described in any one of Claims 1-3 in which a board | substrate, a cathode, an electron carrying layer, an active layer, and an anode are laminated | stacked in this order.   The organic photoelectric conversion element according to claim 1, wherein the cathode is an oxide.   The organic thin-film solar cell containing the organic photoelectric conversion element as described in any one of Claims 1-5.   The organic optical sensor containing the organic photoelectric conversion element as described in any one of Claims 1-5.   A step of forming a coating film by applying a solution containing a polymer containing nitrogen atoms on the cathode, a step of cleaning the surface of the coating film, a step of forming an active layer on the cleaned coating film, And a method of manufacturing an organic photoelectric conversion element including a step of forming an anode   The method for producing an organic photoelectric conversion element according to claim 8, wherein the step of washing is a step of washing using an organic acid.